Mantaray

[JanH]

Not much info on the merits of the Mantaray horns. A few postings on this forum suggests that they sound better (for hifi ?)than sectoral and multicells.
Wich of the Mantarays are considered best for hifi ?
I seems only the MR994A fits the 1" drivers - can the bigger Mantarays be made to fit 1" drivers ?

TIA Jan

[Mirrophonic Sound System]

Give me an exponential horn any day - exponentials
have better low frequency performance (first few
octaves above cut-off).
Good example: Western Electric 24A horn (115hz cut-off)

[Jim D]

Mantaray's and other Contant Directivity Horns, because they are of a conical flare type, are longer for the same LF cutoff than other types such as exponentials.

Exponentials and their dirivitives Radial, Sectoral, Mulitcell and Hypex, Tractrix and
constant flare rate horns unfortunately tend to beam at the upper frequencies. A crude explanation is that once a given frequency's loading is achieved in the horn expansion, it departs the horn. So as the frequenies get higher the horn narrows and therefore the coverage angle gets progessively narrower with frequency. Sectoral/Radial horns attempted to control this by interpolating the exponential flare over a "section" of a circle, with flat sides. Multicells worked because the cells were narrow enough, about 15 degrees, to where the beaming was minimized and MF performace was acheived via multual coupling. Neither type horn was completely successful.

The Manatrays, which are incidentially some of the best CD horns, have frequency performance very much like a plane wave tube, which closely follows the real perfomance of the driver. No Compression driver has flat response, they, depending on design, diaphram type and weight, size start to roll off, at a predictable mathematical rate. The only drivers that do not follow this rate are the Tangerine Phase Plug units which have a somewhat extended HF.
Unlike the beamy exponentials (et al) the Mantaray distributes the HF evenly along the horn front within its angular pattern. The result is, when compared to the older style horns, is an apparent lack of extreme HF. The older horns are brighter only because their waveform is collapsing with frequency and they are beaming in the upper extremitys.

In the world of commercial audio, the Mantarays are more arrayable, predictable, and generally cover better with less units. They do require some HF boost to acheive the same apparent HF level of the older horns. When you drive the Mantaray with one of the Tangerine Phase plug drivers, they sound quite natural without boost. JIM

[Mirrophonic Sound System]

Constant directivity horns such as the Mantaray appear
to be a compound of two horn types: Diffraction & conical.
The first section - diffraction - splatters all frequencies
while the second part acts as a crude waveguide to
control a desired directivity pattern.
One must still question their LF loading above mouth
cut-off.

[JanH]

Hi Jim

Thanks for your extensive explanation of the way the Mantaray horns function compared to the more popular Altec horn types - I think I?ll look for a pair of Mantarays.
Anyone of the Mantarays in particular suited for livingroom hifi ?

MSS thanks for your thaughts on the topic
I am not so much worried by how low the cut-off, actually I think it is more important to get best possible hf extension and dispertion.

Rgds Jan